Packoff assemblies are commonly used in the hydrocarbon production industry to seal various annuli in the wellhead assembly, such as the annulus between a wellhead and a casing hanger which is landed in the wellhead. When the wellhead assembly is configured for drilling operations, a blowout preventer (BOP) or BOP adapter is usually connected to the top of the wellhead, and in this situation a hybrid packoff comprising a lower packoff for sealing between the casing hanger and the wellhead and an upper packoff for sealing between the casing hanger and the BOP or BOP adapter may be employed. Such hybrid packoffs are usually run and landed in the wellhead in one trip and then locked to the wellhead using external lockdown screws. Alternatively, a latching packoff can be run in two trips. However, making two trips to run, land and lock the packoff consumes valuable rig time, and using external lockdown screws requires undesirable penetrations.
Also, after drilling operations are completed, the wellhead assembly is normally converted for use in production operations. This usually requires disconnecting the BOP or BOP adapter from the wellhead and then mounting a tubing head on the wellhead. After the BOP or BOP adapter is removed, the need for the upper packoff no longer exists, and in fact the tubing head usually cannot be mounted on the wellhead with the upper packoff in place due to space constraints in the cellar. Therefore, before the tubing head can be mounted on the wellhead, the hybrid packoff must either be removed and replaced with a single packoff that is configured to seal between the casing hanger and the wellhead or, if the hybrid packoff comprises separate upper and lower packoffs, the upper packoff must be disconnected from the lower packoff and removed. However, both of these options are undesirable. Removing the entire hybrid packoff leaves the annulus between the casing hanger and the wellhead unsealed, and removing just the upper packoff of a two piece hybrid packoff requires the extra step of disengaging the external lockdown screws.